BILLINGS, Mont. — Retired paratrooper Vernon Kinn liked what he heard when Sen. Barack Obama came to Montana recently with a promise to build more health centers for veterans. That could end the 500-mile, roundtrip drive Kinn faces each time he needs a new hearing aid from Montana’s only VA hospital.

But Kinn, who served two years in Vietnam, was unsure he could turn his back on Republican Sen. John McCain, a former Navy pilot who spent five years in a Vietnamese prisoner of war camp.

“It’s going to take a lot of thought. After the war, nobody liked us. They spit on us. Now we’ve got to stick together,” said Kinn, 62.

As the Democratic and Republican presidential campaigns vie for support from the nation’s 25 million veterans, Kinn illustrates the mixed feelings among some in a crucial voting bloc.

Analysts say McCain carries the credentials many veterans look for: two decades of service in the Navy and heroism. While a POW, McCain was tortured repeatedly but refused to give in to his captors’ demands.

To counter McCain’s warrior appeal, Obama, a member of the U.S. Senate Veterans Affairs Committee, has made veterans issues a major theme in his campaign. His trip to Montana — the state with the second-highest proportion of veterans in the country — came on the eve of his nomination.

Obama has also tried to tap into resentment over Iraq, by promising to bring American troops home promptly and divert money now spent on the war to areas like veterans’ health care.

“(McCain) served with honor and distinction,” Obama told Kinn and other veterans at an Aug. 27 town hall meeting in Billings. “We owe him our gratitude. We don’t owe him our vote.”

If veterans agree, that could give Democrats an opening that wasn’t there four years ago, when President Bush captured 55 percent of the veteran vote, said Christopher Parker, a political science professor at the University of Washington.

As the World War II generation ages and the military shrinks in size, veterans’ numbers are on the decline. Yet their political sway remains pivotal, according to Parker and other political analysts.

Veterans cast 16 percent of all votes in 2004. In addition, earning the support of veterans can help burnish a candidate’s national security credentials.

Retired Col. Leo Thorsness is a Medal of Honor winner who for two years shared a room with McCain in the “Hanoi Hilton” prison. Thorsness, who now lives in Alabama, said McCain’s war record gives him an advantage with veterans who will empathize with his experiences.

“In Hanoi, we all had time to think about things. We became much wiser through our suffering,” Thorsness said. “John truly has wisdom, where Obama has knowledge.”

About 200 veterans and family members came to see Obama when he was in Billings. The crowd cheered when Obama pledged to reform treatment programs for combat stress and to funnel more money into educating returning veterans.

Peter Feaver, a former National Security Council staff member now at Duke University, said Democrats in recent years have managed to “out-veteran” the GOP on many issues, by offering some programs more generous than Republicans were willing to support.

“McCain still has the upper hand,” said Feaver, who worked under both Bush and former President Bill Clinton. “But they (Democrats) may not be going for 51 percent of the veteran vote. They may be saying if we can get 40 percent, we’ll take that.”

Kinn, a self-described independent conservative, said allegiance to a fellow veteran weighs on his mind, but that he would back Obama if he decides the Illinois senator can deliver on his promises.

“I was very leery about Obama being a non-veteran. But the things he said, that’s what we need,” said Kinn, who spent 21 years in the Army and suffered substantial hearing loss from being too close to pounding Howitzer cannons.

For other veterans, years of poor health services — epitomized by last year’s scandal at Walter Reed Army Medical Center — have elicited a more clear-cut desire for a change in leadership.

That includes Tracy King of Fort Belknap, who served two years in the Army in the 1970s. After his daughter returned last year from a combat tour in Iraq, King said she was repeatedly turned down for treatment for post-traumatic stress disorder.

“They were willing to sacrifice their lives, then when they get home they have to play the politics,” he said.

King said he was drawn to Obama not so much for his pledges on veterans issues, but for his wider agenda of curbing poverty.

Columbia University political expert Robert Shapiro said the attraction to Obama on other issues offers a lesson for both campaigns. Capturing the veteran vote, he said, could very well come through an appeal on topics not directly connected to their military service.

“Forget the veteran vote and go after the older white male, which will pick up the veterans and others,” Shapiro said.